Roll gauge for gauging external screw threads



p 4, 1951 J. H. NIPER 2,566,356

ROLL GAUGE FOR GAUGING EXTERNAL SCREW THREADS Filed July 8, 1947 2 Sheets-Sheet 1 TJAcua H..NIFER7 J. H. NIPER Sept. 4, 1951 ROLL GAUGE FOR GAUGING EXTERNAL SCREW THREADS Filed July s, 1947 2 Sheets-Sheet 2 Qwucwvtm JAcu a-H N| PER Patented Sept. 4, 1951 UNITED STATES PATENT 2,566,356 OFFICE ROLL GAUGE FOR GAUG'ING EXTERNAL scasw THREADS (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 3 Claims.

The invention described herein may be manufactured and used by or for, the Government for governmental purposes without the payment to me of any royalty thereon. This invention relates to an adjustable gage to check external screwthreads.

The object of this ga e is to provide a means of quickly and accurately checking the pitch diameter of external screw threads at a minimum of expense. This itaccomplishes by being adjustable over a wide range of diameters with only minor adiustments necessary when changing from one diameter to another and by being adjustable over a wide range of thread pitches through the changing of the rollers from one pitch to another.

Figure 1 is a left side view of the gage showing the top roller lowered into gaging position.

Figure 2 is a front view of the gage showing the top roller lowered into gaging position.

, Figure 3is a top view of the gage.

Figure 4 is an end view of the top roller.

Figure 5 is a sectional view of the top roller taken on line 5--5 of Fig. 4.

Figure 6 is a sectional view of the top roller taken on line 6-6 of Fig. 4.

Figure '7 is a sectional view of one of the two bottom rollers.

I is a base which supports the gage and may be provided with four holes 2 with which to fasten it to the inspection table. 3 is a marking disc, held in position by screw 4, on, which may be stamped the size of the rollers being used in the ga e. 5 are the bottom roller supports, which with the axles 6, and axle screws 1, hold the bottom or backing rollers 8 and 9. I0 is a cylindrical surface. extending from the end to the edge of the first ridge on roller 8, whose length is relative to a like surface of different length on roller 9, the lengths of these surfaces being calculated to prevent the insertion of the piece being checked into the gage in such a manner as to cross the threads. and 9, left hand threads may be checked.

A post II, provided to support the indicator I2 and top roller I3, is anchored to the base I by a key I4 and screw I5.

The indicator I2 and top roller I3 are carried on a plate I 6, which is clamped to post II by a locking screw I! and locking bushings I8, and prevented from rotating about the post by key I 9. The indicator I2 and top roller l3 are connected by a shaft 20 riding through a hardened bushing 2i, which is pressed in plate I6. This shaft is prevented from rotating by a screw 23 threaded in plate I6 and having its end engaged in a key way 22 in and extending longitudinally of shaft 29. Indicator I2 has a lug I2a extending from the back of its casing and having a smooth fit within the slotted upper end of shaft 20. A pin I2b passes through aligned apertures in the lug and shaft to secure the indicator to the shaft.

Bv reversing the positions of pieces 8 2 Rotation of the indicator relatively to the shaft is prevented by alocking pin IZc. A yoke 29a is fixed to the lower end of shaft 20. The lower ends of the arms of this yoke have aligned bores in which a shaft 26 is fixed by screws 21. Top roller I3 is journaled on shaft 26.

A coil spring 28 surrounds shaft 26 between yoke 20a and plate or bar I6 and acts to urge upper roller I3, yoke 20a and shaft 20, downwardly. A second coil spring 29, more powerful than 28, encircles the upper portion of shaft- 26 between plate I6 and a collar 30. The collar 30 is slidable on and along shaft 26. Downward sliding movement of collar 30, to compress spring 29, is efiected by wires or links 33 secured to respective opposite sides of collar 30 at their top ends, as clearly shown upon Figure 2. The lower ends of the wires or links are attached to the respective arms of a bail or yoke 32. The ends of these arms are pivoted to bar I6 by screws 34. Upward or counterclockwise pivotal movement of bail 32, as viewed in Figure 1, is limited by a pair of aligned stop pins 35' fixed in. bar l6. Upward sliding movement of collar 30 relatively to shaft or rod 20 may be stopped by engagement of the collar with the casing of indicator I2. Since spring 29 is stronger than 28, when bail 32 is released, collar 30 moves upwardly relatively to shaft 26 until the collar engages the casing of indicator I2; Thereafter, spring 29 acts against, and overpowers, spring 28 to move the indicator, shaft- 20 and gage roller I3, as a unit upwardly. When bail 32 is grasped and pivoted downwardly, spring 29 is compressed, as shown in Figure 1, and shaft 29 and indicator I2 are freed for downward movement under the thrust of spring 28 until roller I3 contacts a specimen to be gaged. By this feature, the roller contacts successive specimens with the same force, and variations otherwise caused by the personal equation due to diiferent gaging forces, are eliminated and more accurate gaging is effected.

The indicator I2 is of the conventional single or offset contact type having a scale 4! and cooperating pointer 42 connected with a contact 31 in any known manner for actuation thereby. Contact 3'! is resiliently pressed by the gage mechanism, against a block 38 fixed on plate I6. Since the plate is rigidly fixed to standard Ill, slight movements of shaft 20 and roller I3, up and down, through plate I6, cause a greatly magnified movement of pointer 42 over scale 4|.

Figure 4 is an end View of the top roller I3. As can be seen inFig. 4, one half of the roller is larger than the other. This is done to create two width of crests 39 and 40 on the ridges as shown in Figs. 5 and 6. The larger diameter is such that it will create a crest 39 whose width is equal to the width of the maximum sized root of an acceptable thread of a given pitch. The smaller diameter is such that it will create a crest 40 whose width is a little greater than the width of the maximum sized root of an acceptable thread of a given pitch. The reason for this type of k roller is explained hereinafter.

To facilitate manufacture the bottom rollers may be made with every other ridge omitted as shown in Fig. 7. The form of the ridges in both the top and bottom rollers corresponds to the form of the thread being checked. The ridges on the rollers are annular in design.

To adjust this gage it i necessary to insert the proper set of rollers for the pitch of the thread being gaged, place the go check plug inposition between the rollers, adjust the position of the rollers, pull down on the bail 32 and identify or note the corresponding position of the dial hand 42 of the indicator 1'2. The no go.check gage is then'substituted for the go check gage and the corresponding position of hand. again noted or identified in any known manner, to thereby determine a permissible range of movement or tolerance between the two positions. r

In operating this gage the piece being checked is placed on the bottom rollers, the handle 32 pulled down and the piece revolved. If during this revolving the dial hand 42 of the indicator 12 remains within the range of movement previi ously determined, the thread on the piece is within its limits.

' The top roller is made with two different width crests, Figs. 4 and 5, to prevent accepting threaded parts'with' a pitch diameter that is under the minimum allowable size. Should the minor diameter of the thread of the specimen being tested, be at its maximum allowable size and its pitch diameter be undersize, when the part of' the upper roller'with the narrower crests of the ridges 39 is riding in the thread of the specimen the indicator will show the thread as being acceptable, but when the juncture between the said base on horizontally spaced axes, a column fixed in and rising from said base, a plate fixed on said column above said base, a shaft carried by said plate for axial translation only toward and from said backing rolls, a gaging roll mounted on the lower end of said shaft for gaging coaction with aid backing rolls, a single contact dial indicator fixed on said shaft and having its operating contact yieldingly engaging said plate for operation by relative translation of said shaft and plate, a-first coil spring acting between said plate and shaft to urge the latter downwardly and move said gaging. roll towardsaid backing rolls, a collar slidably mountedon said .shaft, a second springstronger than said first spring and interposed between said collar and plate,.manuallyoperable bail means carriedby said plate, and a connection between said bail, means and collar. to slide the latter, in response to operation of said, bail means and thereby compress said second. spring and free said shaft and dial, indicator to the action of said first spring. r

. 3. In a screw thread gaging instrument, a normally horizontal base, first and second ridged backing rolls, means mounting said rolls on said base on normally horizontal,.horizontallyespaced parallel axes, a post fixed tosaid baseand rising therefrom, a plate carried by said post for vertical adjustment therealong, a normally vertical shaft mounted vupon saidjplatefor axial translation only in a normally vertical plane between .and

parallel with. the axes of said backing rolls, a

different sized crests is passed there will be a I sharp change in the indicator reading, showing that the gage had been riding on the minor and not the pitch diameter of the specimen thread and therefore that the part should be rejected.

' I claim:

mally horizontal base, first and second ridged backing rolls, means mounting said rolls on said base on normally horizontal, horizontally-spaced parallel'axes, a post fixed to said base and rising therefrom, a plate carried by said post for vertical' adjustment therealong, a normally vertical shaft mounted upon saidplate for axial translation only in a normally vertical plane between direction, and means pivoted on said plate and manually operable to compress said second pring means to free said shaft completely to the action of said first spring means, the actuating contact of said dial indicator contacting said plate for operation by relative vertical translation of said shaft relatively to said plate.

2. In a single or offset contact gaging instrument, "a base, a pair of backing rolls mounted on 1. In a screw thread gaging instrument, a nordial indicator havingan actuating contactand fixed to the upper. end of said shaft,, a third threaded gaging roll journaled upon the lower end of said shaft for movement with said shaft and indicator .in a first direction toward said backing rolls, first spring means urging said shaft in .said .first direction, second spring means stronger than said first spring means and adapted to urge said shaft in a second direction opposite to said first direction, and meanspivoted on said plate and manually operable to compres said second spring means to free saidshaft c0m-. pletelyto the action. of said first spring means, the actuating contact of said dial indicator contacting said plate for operationby vertical trans lation of said shaft relatively to saidplate, said first and second spring means each comprising a compression coil spring surrounding said shaft below vand above said plate, respectively, said manually operable means comprising a bail pivoted on said plate, a collar slidable on said shaft above said second spring, and operating connec tions between said bail and collar.

I V JACOB H jNI PER.

' REFERENCES CITED e The following references are of record in the file Of tIfli'S patent: V

UNITED STATES PATENTS 

